Electric charged particle beam microscope and microscopy

Abstract

An electric charged particle beam microscope is provided in which a specimen movement due to a specimen rotation is classified into a repeatable movement and a non-repeatable movement, a model of movement is determined for the repeatable movement, a range of movement is determined for the non-repeatable movement, the repeatable movement is corrected on the basis of the movement model through open-loop and the non-repeatable movement is corrected under a condition set on the basis of the range of movement.

The invention claimed is: 
     
       1. An electric charged particle beam microscope having an electric charged particle source for generating a first electric charged particle beam, a generator for generating a first electromagnetic field used to lead the first electric charged particle beam to a specimen, a specimen stage for setting position and angle of the specimen in relation to the first electric charged particle beam, a generator for generating a second electromagnetic field used to lead a second electric charged particle beam given off from the specimen to a detector adapted to detect the second electric charged particle beam, and an image former for forming an image indicative of a specimen structure on the basis of a detector output, said microscope comprising a specimen movement corrector including:
 a recording unit for recording the relation between a specimen rotation angle and a specimen movement amount; 
 a display unit for displaying the relation between the specimen rotation angle and the specimen movement amount; 
 a first control unit for determining an amount of specimen movement due to a specimen rotation and correcting it on the basis of the relation between the specimen rotation angle and the specimen movement amount; and 
 a second control unit for determining a specimen movement amount from an image taken before the specimen rotation and an image taken after the correction and correcting it. 
 
     
     
       2. An electric charged particle beam microscope according to  claim 1 , wherein said specimen stage is a specimen stage capable of rotating a projecting specimen, through which the electric charged particle beam transmits to provide a transmission image that can be observed, about the center axis of a projection in all directions. 
     
     
       3. An electric charged particle beam apparatus according to  claim 1 , wherein said display unit for displaying the relation between the specimen rotation angle and the specimen movement amount selects appropriate items from an electric charged particle beam image, a locus of the specimen movement and a movement model determined from the locus and displays them in an overlapping fashion. 
     
     
       4. An electric charged particle beam microscopic method in which a step of irradiating a first electric charged particle beam on a specimen and acquiring an image of the specimen by detecting a second electric charged particle beam given off from said specimen is executed by rotating the specimen in a plurality of directions, comprising:
 a preliminarily measurement step of determining the relation between a specimen rotation angle and a specimen movement amount and recording it in advance; 
 an analysis step of calculating an amount of specimen movement due to a specimen rotation from the recorded relation between the specimen rotation and the specimen movement amount and correcting the calculated specimen movement amount; 
 a first correction step for correcting specimen movement in accordance with calculated value of specimen movement amount by slanted specimen; 
 a second correction step of determining a correction error in the first correction step from an image taken before the specimen rotation and an image taken after the correction and correcting the error; and 
 an image pickup step of taking an image of a specimen structure and recording it after the first and second correction steps. 
 
     
     
       5. An electric charged particle microscopic method according to  claim 4 , wherein said preliminary measurement step includes the steps of:
 measuring a specimen movement in an XY plane orthogonal to an electric charged particle beam incident direction; 
 assuming a three-dimensional model of specimen movement; 
 fitting the three-dimensional model to a specimen movement in the XY plane; and 
 calculating a specimen movement in Z direction parallel to the electric charged particle beam incident direction from the fitted three-dimensional model. 
 
     
     
       6. An electric charged particle beam microscopic method according to  claim 4 , wherein the diameter of a view-field used in said second correction step is so set as to be wider than a correction error range in said first correction step estimated from a difference between a recorded sample movement and a calculated sample movement amount. 
     
     
       7. An electric charged particle beam microscopic method according to  claim 4 , wherein said second correction step includes the steps of:
 calculating conditions for positional displacement measurement and defocus measurement on the basis of a correction error generated in said first correction step and a correction error permissible in said image pickup step; and 
 displaying a warning message when conditions designated by an operator differ from the calculated conditions.